The use of additional supplement can affect ruminant performance by increasing the animal weight gain and maximizing profits from the activity. Thus, the objective of this study was to evaluate the influence of protein-energy supplementation on microbial synthesis, animal performance, nutrient digestibility, and body composition of Brangus x Zebu steers on pasture. The experiment lasted 160 days and included 36 animals divided into two groups; 18 steers received protein-energy supplementation (PES), and the other 18 received non-supplementation (NPES). Individual pasture intake and nutrient digestibility were estimated using the double indicator technique-chromium oxide and lignin in potassium permanganate. Spot urine samples were collected from 36 animals to determine creatinine, allantoin, and uric acid concentrations. All animals were slaughtered at the end of the experiment to evaluate body composition. There was increase in intake (P < 0.001) and dry matter digestibility (P = 0.01); it resulted in higher animal weight gain (P < 0.001) receiving supplementation. However, there was no difference (P > 0.05) in pasture nutrient intake between treatments. Supplementation increased microbial nitrogen (P < 0.001). For body composition, the model identity test that was applied showed no difference (P > 0.05) between the models, so it was adopted a common equation for both treatments. There was no difference (P > 0.05) for body composition between treatments. Therefore, the use of protein-energy supplementation for steers on pasture allowed higher microbial protein synthesis and better utilization of nutrients, which resulted in better animal performance. The use of protein-energy supplementation at 0.6% BW did not alter the carcass composition of Brangus x Zebu steers. However, it recommends protein-energy supplementation in pasture systems during the rainy period or using an irrigation system.

中文翻译：

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Brangus x Zebu牛在补充营养的热带牧场上的性能，消化率，微生物蛋白合成和身体成分。

使用额外的补充剂可以通过增加动物的体重增加并从该活动中获得最大利润来影响反刍动物的表现。因此，本研究的目的是评估蛋白质能量补充对牧场上Brangus x Zebu ers牛的微生物合成，动物性能，营养消化率和身体成分的影响。实验持续了160天，包括了36只动物，分为两组。18头牛获得了蛋白质能量补充（PES），其余18头获得了非补充能量（NPES）。使用双指示剂技术（高锰酸钾中的氧化铬和木质素）估算了各个草场的摄入量和养分消化率。从36只动物中收集了尿液样本，以确定肌酐，尿囊素和尿酸浓度。在实验结束时将所有动物屠宰以评估身体组成。摄食量（P <0.001）和干物质消化率（P = 0.01）增加；它导致补充了更高的动物增重（P <0.001）。然而，处理之间的牧草营养摄入量没有差异（P> 0.05）。补充增加了微生物氮（P <0.001）。对于身体成分，所应用的模型同一性测试显示模型之间没有差异（P> 0.05），因此两种处理均采用了一个公共方程式。两次治疗之间的身体组成没有差异（P> 0.05）。因此，在牧场上使用蛋白质能量补充剂可以增加微生物的蛋白质合成量，并更好地利用养分，从而使动物表现更好。体重为0.6％的蛋白质能量补充剂的使用不会改变Brangus x Zebu ers牛的car体组成。但是，建议在雨季或使用灌溉系统的牧场系统中补充蛋白质能量。